Effect of volcanic aerosols on stratospheric ozone at Kodaikanal

Abstract

Nimbus 7 SBUV data (average of zonal means for 5-10°N and 10-15°N) and Dobson data over Kodaikanal (10° N latitude) for the period 1979-1994 have been analysed to study the effect of El-Chichon and Pinatubo volcanic eruptions on ozone quasi-biennial oscillation (QBO). The ozone QBO has been found to be disturbed up to the height of 34 km following

both the eruptions and the effect persisted even after one year of the event. The impact of El-Chichon volcanic eruption on ozone shows a depletion up to 34 km with maximum effect at 29 km, whereas the impact following Pinatubo eruption shows ozone depletion up to 29 km above which an increase in ozone is observed. The cause of depletion below about 27 km is

due to well known heterogeneous chemistry. The cause of ozone depletion above 27 km following the two major eruptions has been investigated. The percentage change in ozone has been estimated after taking the warming due to aerosol into consideration. The theoretically calculated and the observed percentage deviations of ozone show good agreement in the

<span style="font-size:12.0pt;line-height:115%;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-in;mso-bidi-language:hi"="" lang="EN-IN">case of El-Chichon eruption, while for Pinatubo eruption the calculated values show more negative values.</span>